Devices for incubating a liquid sample at uniform temperatures above or below ambient temperature are commonly required during the processing steps and procedures of different standard assays. A thermal incubation device typically includes an element that heats or cools the bottom and sides of a container holding the liquid sample, thereby bringing the sample to its desired incubation temperature. The top of the container is often unable to achieve the desired incubation temperature because it is not in direct contact with the heating or cooling element. The unwanted temperature gradient may lead to significant amounts of condensation collecting at the top of the sample container. The condensation in the sample container may result in an unwanted reduction in the sample volume. In a standard assay, a reduction in sample volume can lead to altered reaction conditions, which may negatively influence the assay results.
Approaches for minimizing condensation during sample incubation at a temperature above or below ambient temperature are known in the art. Thermal cycling devices, which often incubate liquid samples at elevated temperatures, may additionally include a heated cover that directly contacts the closed top of the reaction tube and heats the top to a temperature equivalent to or hotter than the sides of the tube. Alternatively, the liquid sample may be overlaid with mineral oil or a similar reagent to create a physical vapor barrier during the incubation.
The above approaches, however, have limitations that generally prevent them from being completely effective. An element such as a heated cover prevents facile access to the sample during the incubation process. The use of mineral oil may not be compatible with the assay conditions and also makes access to the sample cumbersome. Both solutions severely limit the ability of the incubation process to be efficiently automated.
It is therefore important to develop an alternative means of minimizing condensation of samples during the incubation process. Accordingly, there is an unmet need in the field for a device that provides an effective solution to the problem of sample condensation during thermal incubation, while not suffering from the limitations of the prior art.